Redundant communications for multi-chip systems

ABSTRACT

An electronic device, comprising: a first component configured to transmit a first set of data to a second component by providing a first memory request specifying the first set of data for and an input memory address, and a transaction tracking unit coupled to a first transport interface, the transaction tracking unit configured to: receive the first memory request; transmit a second memory request that specifies at least a first portion of the first set of data, via the first transport interface, to the second component; receive a response to the second memory request from the second component; determine that the response corresponds to the second memory request; and provide, to the first component, an output response based on the received response to the second memory request.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to India Provisional Application No.202041047260, filed Oct. 29, 2020 which is hereby incorporated byreference.

BACKGROUND

Machine learning (ML) is becoming an increasingly important part of thecomputing landscape. Machine learning is a type of artificialintelligence (AI) and ML helps enable a software system to learn torecognize patterns from data without being directly programmed to do so.Neural networks (NN) area type of ML which utilize a set of linked andlayered functions (e.g., node, neuron, etc.) which are weighted toevaluate input data. In some NNs, sometimes referred to as convolutionneural networks (CNNs), convolution operations may be performed in NNlayers based on inputs received and weights CNNs are often used in awide array of applications typically for recognition and classification,such as image recognition and classification, prediction andrecommendation systems, speech and language recognition and translation,etc.

As ML become increasingly useful, there is a desire to execute multiplecomplex ML techniques, such as NNs and CNNs, efficiently in devices witha high degree of availability. For example, for a partially or fullyautomated driving application, multiple ML models may be executedconcurrently and in real-time to identify, recognize, and/or predictobjects, paths, trajectories, etc. These ML models may need to beavailable for use, even if there are issues that could impact theperformance of the ML models, such as partial hardware failure,performance degradations for example due to a large number of inputs,inclement weather conditions, etc.

SUMMARY

This disclosure relates to an electronic device, comprising: a localcomponent configured to transmit a first set of data to a secondcomponent by providing a first memory request specifying the first setof data for and an input memory address, and a transaction tracking unitcoupled to a first transport interface, the transaction tracking unitconfigured to: receive the first memory request; transmit a secondmemory request that specifies at least a first portion of the first setof data, via the first transport interface, to the second component;receive a response to the second memory request from the secondcomponent; determine that the response corresponds to the second memoryrequest; and provide, to the first component, an output response basedon the received response to the second memory request.

Another aspect of the present disclosure relates to a circuitcomprising: a transaction tracking unit configured to: receive a firstmessage from a remote component via a first transport interface; and amemory mapped port coupled to the tracking unit, the memory mapped portconfigured to: output the first message to a local component; receive aresponse from the local component; wherein the tracking unit is furtherconfigured to: determine that the received response corresponds to thefirst message from the remote component; and output at least a firstportion of the response to the remote component via the first transportinterface.

Another aspect of the present disclosure relates to method fortransmitting data, the method comprising: receiving, from a firstcomponent, first data associated with a mapped input memory address totransmit to a second component; transmitting at least a first portion ofthe first data, via a first transport interface, to the secondcomponent; recording a status of the transmission to the secondcomponent; receiving a response to the transmission from the secondcomponent; determining that the response corresponds to the recordedtransmission; and providing the response to the first component.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of various examples, reference will now bemade to the accompanying drawings in which:

FIG. 1 is a block diagram of processing systems coupled via redundantcommunications paths, in accordance with aspects of the presentdisclosure.

FIG. 2 is a block diagram illustrating data flows, in accordance withaspects of the present disclosure.

FIGS. 3A-3D are block diagrams illustrating example operating modes forthe transaction tracking and distribution module (TTDM), in accordancewith aspects of the present disclosures.

FIG. 4 is a block diagram of a TTDM in a transmit mode of operation, inaccordance with aspects of the present disclosure.

FIG. 5 is a table illustrating a transaction mapping table, inaccordance with aspects of the present disclosure.

FIG. 6 is a block diagram of a TTDM in a receive mode of operation, inaccordance with aspects of the present disclosure.

FIG. 7 is a block diagram illustrating data flow between TTDMs, inaccordance with aspects of the present disclosure.

FIG. 8 is a flowchart illustrating a technique for transmitting data, inaccordance with aspects of the present disclosure.

DETAILED DESCRIPTION

Increasingly, software, including ML techniques, are being used insystems where a high degree of availability is desired, such as safetyor mission critical systems. Additionally, the software used in suchsystems is becoming increasingly complex and may represent an increasedcomputing workload. Often, such systems may be scaled to handleincreased workloads by parallelizing systems, such as by having multiplecompute cores, such as multiple central processing unit (CPU) cores,higher and lower powered CPU cores, ML cores, graphics processing unit(GPU) cores, as well as increased memory, communication links, etc.,allowing multiple software modules to run in parallel. Having multiplecores helps performance scaling and provides a level of redundancy. Forexample, multiple cores help provide redundancy in case one or more CPUsfail. As another example, multiple cores may also help increaseperformance of chained software, where an output of one software modulemay be input to another module running in parallel. In some cases, aredundant communications path may be provided to help increaseredundancy and availability.

FIG. 1 is a block diagram 100 of components coupled via redundantcommunications paths, in accordance with aspects of the presentdisclosure. As used herein, components include electronic devices whichmay access another component via a transport interface. As an example,components that may access other components may include processors,processor packages, controllers, direct memory access/input outputdevices, etc. Components which may be accessed may include otherprocessors, processor packages, and/or controllers and may also includeI/O devices, network devices, memory such as double data rate randomaccess memory and/or other types of random-access memory, etc. As shown,block diagram 100 includes a first component 102, such as a processorcore, which may be executing a first application 104, such as a ML modelor other software. In some cases, there may be a desire to transmit datato a second component 106, such as another processor core, for examplefor a second application 108, which may be any software executing on thesecond component 106, including another instance of the firstapplication 104. This first application 104 may transmit information tothe second application 108 via a first transaction tracking anddistribution module (TTDM) 110. The TTDM 110 may accept information viaa proxy memory window presented as a mapped memory region to which anapplication or other process may read, write, and/or otherwise provide amemory request to. The first application 104 may pass information to theTTDM 110 by initiating a transaction, such as a read or write request,to the mapped memory region managed by the TTDM 110.

The mapped memory region of the TTDM may provide access to transportinterfaces via the TTDM. These mapped memory regions may correspond tomemory (e.g., cache memory, registers, DRAM (dynamic random-accessmemory), etc.) of the first TTDM 110, rather than local memory. Themapped memory region may be configurable in size and may includemultiple regions rather than a single continuous region. In some cases,one or more portions of the mapped memory region may be reserved fortransmitting data to other components via the first TTDM 110 and anotherone or more portions may be reserved for receiving data from othercomponents via the first TTDM 110. In some cases, one or more portionsof the mapped memory region may be reserved for instructions to thefirst TTDM 110 and another one or more portions may be reserved for datato be transmitted to the other component. Using a mapped memory regionto transmit and/or receive data with another component helps abstractthe transport protocol from the application and helps allow theapplication to function with a variety of transport technology.

After the first TTDM 110 receives the information, the first TTDM 110then transmits one or more portions of the information to a second TTDM112 of the second component 106 via one or more transport technologies.Transport technologies provide a data path between components. Examplesof transport technologies include bus architectures, such as peripheralcomponent interconnect (PCI) bus, ethernet, HyperLink transport, etc.The first TTDM 110 is coupled to multiple transport technologies, here afirst transport technology 114 and a second transport technology 116.Multiple transport technologies may help provide redundancy forcommunications paths. The first TTDM 110 may determine whether totransmit messages from the first application 104 to the second TTDM 112and the second application 108 via one of, or both of, the transporttechnologies 114 and/or 116. For example, the first TTDM 110 mayreplicate the message and transmit the message on both the firsttransport technology 114 and the second transport technology 116.

FIG. 2 is a block diagram 200 illustrating data flows, in accordancewith aspects of the present disclosure. In this example, a SoC 202 mayinclude a first set of CPU cores 204. In some cases, the SoC 202 mayalso include a second set of CPU cores 206. This second set of CPU cores206 may be used to supplement the first set of CPU cores 204, forexample, by offering lower performance but consuming less power than thefirst set of CPU cores 204, or by being optimized for certain types ofworkloads, such as real-time or safety applications. The SoC 202 mayalso include one or more DSP and/or ML cores 208 and a memory 210. TheSoC 202 includes an interconnect 212, which couples the components ofthe SoC 202 together and provides communications as between thecomponents. The SoC 202 also includes a memory controller module 214which includes a TTDM 216. The SoC 202 also includes a set of transportinterface peripherals 218. The transport interface peripherals 218 mayinclude one or more components which allow data to be transmitted orreceived and may be accessed using a mapped memory region. In thisexample, the transport interface peripherals 218 include a first PCIexpress (PCIe) interface 220, a second PCIe interface 222, a firstHyperLink interface 224, and a second HyperLink interface 226. It may beunderstood that the components included in the transport interfaceperipherals 218 here are examples and other components accessible viathe transport technologies may also be included in the transportinterface peripherals 218.

The TTDM 216 may act as a proxy for communications between components.For example, where a component such as a CPU core of the first set ofCPU cores 204 wants to transmit data to another component, such as asensor coupled via the PCIe interfaces 220 and 222 and/or HyperLinkinterfaces 224 and 226, the CPU core may write 240 the data, along withaddress information and/or an indication of how to transmit the data, toa memory region mapped to the TTDM 216. The TTDM 216 may, based on theaddress information and/or indication of how to transmit the data,determine an appropriate transport technology to use. In some cases,policies regarding how to transmit the data may be previouslyconfigured. In this example, the TTDM 216 may determine that the data isintended for a component coupled to via the PCIe interfaces 220 and 222and the HyperLink interfaces 224 and 226, for example based on theaddress information. The TTDM 216 may determine which interface to usebased on, for example, the indication of how to transmit the data PCIeinterfaces 220 and 222 and/or HyperLink interfaces 224 and 226 aconfiguration of the TTDM 216. The TTDM 216 then convert the data into aformat compatible with the determined interface. For example, if theTTDM 216 determined to transmit the data via the second PCIe interface222, the TTDM 216 may convert the data into a format compatible withPCIe. Similarly, if the TTDM 216 determined to transmit the data viaboth a PCIe interface and a HyperLink interface, the TTDM 216 wouldconvert the data to a format compatible with PCIe and convert a copy ofthe data to a format compatible with HyperLink. The TTDM 216 thentransmits 242 the data via the determined interface. A response 244 maybe received via one or more interfaces, such as PCIe interfaces 220 and222 and/or HyperLink interfaces 224, by the TTDM 216. The TTDM 216 maythen forward 246 the response to the CPU core.

The SoC 202 in this example also includes a set of standard peripherals228 which provide connectivity, services, and/or interfaces that areoften available for an SoC 202. In this example, the set of standardperipherals 228 include a universal serial bus (USB) 230 multimedia card(MMC) 232, display 234 connectivity, as well as graphical operations236, for example, via a GPU or other image processing hardware. In somecases, the set of standard peripherals 228 may include components whichmay be coupled to and accessible by the transport interface. Suchcomponents of the standard peripherals 228 may initiate and participatein transactions with other components, such as a processor core via theTTDM 216.

FIGS. 3A-3D are block diagrams illustrating example operating modes forthe TTDM, in accordance with aspects of the present disclosures. In somecases, the TTDM may support multiple operating modes for transmittingand receiving data. In some cases, the TTDM may be preconfigured tooperate in certain operating modes, or the operating mode on the TTDMmay be configurable. For example, the TTDM switch among the supportedmultiple operating modes based on which sub-region of a memory mappedregion of the TTDM a memory operation is received in. In FIG. 3A, a TTDM302 may be configured to operate in a load balancing mode. In this loadbalancing mode, the TTDM 302 may receive input data from a component304. The TTDM 302 may then determine which transport technology 306 touse. This determination may be based on, for example, an amount of loadon the transport technologies 306. For example, the TTDM 302 may trackan amount of data received on the various transport technologies 306 andthen determine to use a transport technology associated with a loweramount of data being transported. In some cases, the amount of load onthe transport technology may be inferred rather than directly measured.For example, the TTDM 302 may determine which transport technology ofthe transport technologies 306 to use based on a pattern or rotation.The TTDM 302 may transmit a first set of data on a first transporttechnology, a second set of data on a second transport technology, andso on. In some cases, the TTDM 302 may split data received from thecomponent 304 into multiple sets of data and transmit the sets of dataover different transport technologies. 302. The TTDM 302 may include anindication for how to combine the data with the transmitted sets ofdata. A second TTDM (not shown) may receive and combine the split setsof data based on the indication for how to combine the data beforeforwarding the data to a target component (e.g., remote component).

In FIG. 3B, the TTDM 302 may be configured to operate in a regulatedbandwidth mode. In this regulated bandwidth mode, the TTDM 302 mayreceive data from a peripheral 312. The data may include a credentialindication 314. The TTDM 302 may prioritize and/or determine whichtransport technology to transmit the data to a target component 316based on the credential indication 314. As an example, the data mayinclude a credential indication 314 indicating a priority associatedwith the data. Data associated with a higher priority credential maythen be transmitted by the TTDM 302 via the transport technology beforedata associated with a lower priority credential. As another example,when there are multiple transport technologies, the TTDM 302 maytransmit data associated with a higher priority credential via adifferent transport technology as compared to data associated with alower priority credential, thus helping provide differential handlingfor quality of service. In yet another example with multiple transporttechnologies, the TTDM 302 may transmit data associated with a highersecurity credential via a different transport technology as compared todata associated with a lower security credential.

In FIG. 3C, the TTDM 302 may be configured to operate in an any receivedresponse mode. In this any received response mode, the TTDM 302 mayreceive data from a component 322 for transmission to a targetcomponent. The TTDM 302 may then transmit multiple copies of the datavia multiple transport technologies, including a first transporttechnology 324, and a second transport technology 326. In this example,copies of the data are transmitted on the first transport technology 324and the second transport technology 326. A TTDM of a target component(not shown) may receive one or more copies of the transmitted data andforward the data to the target component. The target component may thentransmit a response to the component 322 via the TTDM of the targetcomponent. The TTDM of the target component may use one or more of thetransport technologies. In some cases, the responses may be transmittedusing the same transport technologies used to transmit the data or asame number of transport technologies as used to transmit the data. Inother cases, the response may be transmitted using a different set ofone or more transport technologies.

In this example, the response should be transmitted via the sametransport technologies used to transmit the data, e.g., the firsttransport technology 324 and the second transport technology 326. Asshown in this example, a response is not received via the secondtransport technology 326 for some reason. A response may not bereceived, for example, if the second transport technology 326 failed totransmit the data to the TTDM of the target component, or the secondtransport technology 326 failed to transmit the response to the TTDM302. In the any received response mode, the TTDM 302 may proceed totransmit the response to the component 322 if any response is received.In some cases, if multiple responses are received, the TTDM 302 maytransmit the first received response to the component 322 and discardany later received responses. In some cases, if the TTDM 302 expects aresponse on the second transport technology 326 and does not receive aresponse within a time window, the TTDM 302 may transmit an indicationthat the second transport technology 326 has failed, for example, toraise a warning. It may be understood that the multiple transporttechnologies 324 in this example may be less than all of the transporttechnologies coupled to the TTDM 302. It may be understood that the datamay refer to a request for data from the target component and/or datafor the target component, and the response may refer to the datarequested from the target component, an error message, and/or anacknowledgement response.

In FIG. 3D, a TTDM 302 may be configured to operate in a best ofN-response mode. The initial transmission of data from a component 332via the TTDM 302 through a first transport technology 334, and a secondtransport technology 336, as well as response by a target component viaassociated TTDM of the target component (not shown) may be substantiallysimilar to that discussed above with respect to the any receivedresponse mode. In this example, the response may be transmitted via thesame transport technologies used to transmit the data, e.g., the firsttransport technology 334 and the second transport technology 336. Asshown in this example, a response is corrupted via the second transporttechnology 336 for some reason. A response may be corrupted, forexample, via electrostatic discharge, radiation induced errors, bitflips, etc.

In the best of N-response mode, the TTDM 302 may include comparatorlogic 328 which compares the responses received from the transporttechnologies. The comparator logic 328 may compare the responsesreceived to determine which response is the most commonly receivedresponse. For example, if the TTDM 302 receives responses from threetransport technologies and two of the responses match, the TTDM 302 mayproceed to transmit one of the matching responses to the component 332.In cases where there are an equal number of non-matching responses, thecomparator logic 338 may detect an error and may take corrective action.In this example, the comparator logic 338 may compare the responsereceived via the first transport technology 334 to the corruptedresponse received via the second transport technology 336 and determinethat the two responses differ, indicating that there was an error in thetransmission. The TTDM 302 may then take corrective action, such as byrequesting a retransmission, or transmit an indication that an error wasdetected. If, for example, instead of a corrupted response from theabove example, a response is received via the first transport technology334 and no response is received via the second transport technology 336,the TTDM 302 may proceed to transmit the response to the component 332as there was no response to compare the received response against.

FIG. 4 is a block diagram 400 of a TTDM 450 in a transmit mode ofoperation, in accordance with aspects of the present disclosure. In FIG.4 , portions of the TTDM 450 used during a transmit operation are shownand it may be understood that a TTDM may include portions illustrated inboth TTDM 450 of FIG. 4 and TTDM 650 of FIG. 6 . As shown, the TTDM 450includes a component port 402 which may be coupled to a requestingcomponent (e.g., local component). The component port 402 is coupled toa transaction tracker module 404, which includes a tracking whiteboard406 and an input/output (I/O) buffer 408. The tracking whiteboard 406may maintain a list of outstanding transactions of the TTDM 450,tallying transactions transmitted to the target component againstresponses from the target component. The I/O buffer 408 may store databeing read from/written to the target component.

The component port 402 may also be coupled to other components, such asa distributor module 412, to help pass input information, such ascredential information, to the other components. The transaction trackermodule 404 is coupled to a transaction mapping table 410, a distributormodule 412, and a response handler module 414. The transaction mappingtable 410 is coupled to and receives configuration input from aconfiguration port 416. The transaction mapping table 410 helps tracktransactions and may include a mapping as between the mapped memoryaddress from the component port 402 to the target component addressspace. The configuration port 416 is also coupled to a set of controland status memory mapped registers 418 configured to store control andstatus information for the TTDM 450. The transaction mapping table 410may be coupled to and access the set of control and status memory mappedregisters 418 to help manage the operating modes.

The distributor module 412 may include a transaction generator module420, a timeout handler module 422, and a load balancer module 424. Thedistributor module 412 may act as a configurable policy engine formanaging the operating modes of the TTDM 450. The timeout handler module422 may implement a timeout state machine for tracking whetheroutstanding transactions have timed out. The load balancer module 424may help balance transactions across multiple transport technologies andmay be configured to help manage credit based load balancing, ratelimiting based on the transport technology or rate limited based on atype of data as determined by credentials associated with the data. Thedistributor module 412 and the response handler module 414 may becoupled to a transport port 426. The transport port 426 may be coupledto one or more transport technologies (not shown).

The TTDM 450 may be configured via the configuration port 416. Theconfiguration port 416 may be mapped to a configuration memory regionsuch that writes to the configuration memory region are input to theconfiguration port 416. In some cases, the configuration memory regionhas a memory address separate from the mapped memory region of the TTDM450, which may be used for input/output operations.

In some cases, the mapped memory region of the TTDM 450 may include twoor more sub-regions that may correspond to various functions. Forexample, sub-regions may correspond with the different operating modesof the TTDM 450. For example, writing data to one sub-region maycorrespond to an indication to transmit the written data via the loadbalancing mode, while writing data to another sub-region may correspondto an indication to transmit the written data via a best of N responsemode. The transaction mapping table 410 may help track the mapping ofthe input from these sub-regions and the request sent to the targetcomponent.

As an example, a write request {WR, A} to write data to a particularlocation A on a target component may be received on the component port402 at in certain memory sub-range of the mapped memory range of theTTDM 450. This write request may be recorded into the trackingwhiteboard 406 of the transaction tracker module 404 and the writerequest may be transmitted to the distributor module 412. Thetransaction tracker module 404 may also transmit 428 the memorysub-range in which the write request is received to the transactionmapping table 410. The transaction mapping table 410 may then determinean operating mode corresponding to the memory sub-range in which thewrite request was received. The transaction mapping table 410 maytransmit an indication of the operating mode to the transactiongenerator 420. Based on the indicated operating mode, the transactiongenerator may address and translate the write request into a formatcompatible with one or more transport technologies and send thetranslated write request to the transport port 426 for output to the oneor more transport technologies. As an example, if the operating modeindicates that copies of the write request should be transmitted overtwo transport technologies, the transaction generator 420 may generatetwo copies of the write request and transmit 430 these two copies of thewrite request to the transport port 426 for output to the addressedtransport technologies. A first copy {Wr,A1} of the write request may beaddressed A1 to a first transport technology of the two transporttechnologies. A second copy {Wr,A2} of the write request may beaddressed A2 to a second transport technology of the two transporttechnologies. The tracking whiteboard may be updated 432 to indicatethat the write request for address A was sent on address A1 of the firsttransport technology and sent on address A2 of the second transporttechnology and the requests are both pending (e.g., [A, {A1, pend}, {A2,pend}]).

Continuing the example, the target component may perform the writerequest and transmit responses back via the first transport technology{RespWR,A1} and the second transport technology {RespWR,A2}. Theseresponses may be received at the transport port 426 and transmitted 434to the response handler 414. The response handler 414 may tally theresponses based on the operating mode of the TTDM 450. In this example,the TTDM 450 may be in the any one response operating mode and when aresponse is received via either the first transport technology or thesecond technology, the response handler 414 may store the response inthe I/O buffer 408. The tracking whiteboard 406 may be updated toindicate that a response has been received for the write request. Forexample, if a response has been received via the first transporttechnology, but has not yet been received via the second transporttechnology, the tracking whiteboard 406 may be updated as [A, {A1,received}, {A2, pend}]. In some cases, the tracking whiteboard 406 mayrecord information regarding the operating mode associated with atransaction. This information may used to determine when a response tothe requesting component is appropriate (e.g., when a single response isreceived, when a best of N responses is determined, etc.) and theresponse transmitted 436 for output by the component port 402.

FIG. 5 is table 500 illustrating a transaction mapping table, inaccordance with aspects of the present disclosure. The transactionmapping table may be included in a transaction tracker module and thetransaction mapping table maps certain sub-regions of the memory mappedregion to certain operating modes of the TTDM. As shown, the transactionmapping table may include information defining multiple regions 1, 2, .. . N corresponding to the operating modes supported by the TTDM. Eachsub-region may be associated with a base memory address, a size of thesub-region, an operating mode corresponding with the region, and anyparameters associated with the operating mode. In some cases, theoperating modes supported by the TTDM may be predefined, while aspectsof the operating modes, such as the location, size, and operating modeassociated with certain sub-regions may be configured, for example, viaconfiguration information received via the configuration port.

FIG. 6 is a block diagram 600 of a TTDM 650 in a receive mode ofoperation, in accordance with aspects of the present disclosure. In FIG.6 , portions of the TTDM 650 used during a receive operation are shownand it may be understood that a TTDM may include portions illustrated inboth TTDM 450 of FIG. 4 and TTDM 650 of FIG. 6 . As shown, the TTDM 650includes a transport port 602 which may be coupled to one or moretransport technologies (not shown) to a requesting component (e.g.,remote component). As with TTDM 450, for TTDM 650, transport port 602 iscoupled to a transaction tracker module 604, which includes a trackingwhiteboard 606 and an input/output (I/O) buffer 608. The trackingwhiteboard 606 may maintain a list of outstanding transactions of theTTDM 650, tallying transactions transmitted to the target componentagainst responses from the target component. The I/O buffer 608 maystore data being read from/written to the target component.

The transaction tracker module 604 is coupled to a transaction mappingtable 610, a distributor module 612, and a response generator module614. The transaction mapping table 610 is coupled to and receivesconfiguration input from a configuration port 616. The transactionmapping table 610 helps track transactions and may include a mapping asbetween the input received from a source component from the transportport 602 to the component address space. The configuration port 616 isalso coupled to a set of control and status memory mapped registers 618configured to store control and status information for the TTDM 650. Thetransaction mapping table 610 may be coupled to and access the set ofcontrol and status memory mapped registers 618 to help manage theoperating modes. The distributor module 612 may include a transactiongenerator module 620 and a timeout handler module 622. The distributormodule 612 may act as a proxy to generate local transactions to themapped target memory region of the target component. The timeout handlermodule 622 may implement a timeout state machine for tracking whetheroutstanding transactions have timed out. The distributor module 612 maybe coupled to a component port 626 and the component port 626 may becoupled to the target component (e.g., local component). The componentport 626 may be coupled to the transaction tracker module 604, and thetransaction tracker module 604 may be coupled to the response generator614. The response generator 614 may be coupled to the transport port602. The response generator 614 may include a state machineimplementation for generating responses to the source component and mayimplement the configurable operating modes on the target TTDM 650 side.

Tracing the operation of the target TTDM 650 for when a write request isreceived, a number N of write requests may be received at the transportport 602 from the source TTDM, such as TTDM QE02. Continuing theprevious example discussed in conjunction with TTDM QE02 and FIG. QE,two copies of the write request, {Wr,A1} and {Wr,A2} may be received viathe first transport technology and the second transport technologyrespectively at the transport port 602. The write requests may be passedto the transaction tracker module 604 with an indication of a sourcetransport technology the write request was received on (e.g.,{Wr,A,Src_A1}, {Wr,A,Src_A2}). The tracking whiteboard 606 may beupdated to record that a write request for address A was received onaddress A1 of the first transport technology and also received onaddress A2 of the second transport technology, and a status of the writerequest (e.g., [A, {SRC_A1, received}, {SRC_A2, received}]). The addressA of the received write request may be sent to the transaction mappingtable 610 where the address of the write request may be translated to acorresponding address of the target component. This translated addressmay be input to the transaction generator module 620 to generate anappropriate write request (e.g., Wr, A}) for output on the componentport 626 to the target component. In cases where multiple write requestsare received to the same address, the transaction generator module 620may merge the multiple write requests to a single write request for thetarget component. For example, the transaction generator module 620 maytrack outstanding requests sent to the target component.

The target component, in response to the write request, may output asingle response (e.g., Resp{Wr,A}) that is input to the TTDM 650 at thecomponent port 626. The response may be input from the component port626 to the transaction tracker module 604. The tracking whiteboard maybe updated to indicate that a response from the target component hasbeen received (e.g., [A, {SRC_A1, resp.}, {SRC_A2, received}]). In somecases, if the transaction tracker module 604 receives another copy ofthe write request associated with a write request that has already beencompleted, such as from another transport technology, the transactiontracker module 604 may drop the copy of the write request. Thetransaction tracker module 604 may output to the response generator 614,the response to the write request and an indication of the transporttechnolog(ies) to use to send the response to the write request (e.g.,Resp{Wr,A1}, Resp{Wr,A2}). In some cases, output for the responsegenerator 614 may be buffered in the I/O buffer 608. For example, if theresponse generator 614 has queued responses to send or is busy, responseto the write request may be temporarily buffered. In some cases, theindication may be based on the transport technologies from which thewrite request was received on. The response generator 614 may thengenerate copies of the write requests for the corresponding transporttechnolog(ies) and output the write requests to the transport port 602to the appropriate transport technolog(ies).

FIG. 7 is a block diagram 700 illustrating data flow between TTDMs, inaccordance with aspects of the present disclosure. Diagram 700illustrates data flows for a memory read request from a requesting TTDM702 to a target TTDM 704. The requesting TTDM 702 may receive a readrequest 706 (e.g., {Rd,A}) from a requesting component (not shown) foraddress A for a target component. After receiving the read request 706,a tracking whiteboard 708 of a transaction tracker module 710 may beupdated. The tracking whiteboard 708 may record information includingthe read address of the read request (e.g., Addr), as well as addressinformation (e.g., addr) and request status (e.g., status) for copies ofthe read request (R1, R2) that may be sent over different transporttechnologies. In this example, two copies of the read request to addressA may be translated to address A1 corresponding to an address space forthe first transport technology and address A2 corresponding to anaddress space for the second transport technology. The trackingwhiteboard 708 may record that the read request is associated with acopy of the read request addressed to A1 and copy of the read requestaddressed to A2 both of which are pending (e.g., [A, {A1, pend}, {A2,pend}]). A writeback index of the tracking whiteboard 708 may be used toidentify where in the tracking whiteboard 708 the entry corresponding tothe read request is located. The transaction tracker module 710 may alsoallocate 750 space in an receive buffer 752 (e.g., I/O buffer) to storeresponses to the copies of the read requests. The receive buffer 752 mayalso include the addresses that the read requests were sent on, apointer to the first in first out buffer space (FIFO) for the response,and a write back pointer to the tracker whiteboard 708 index. The twocopies of the read request (e.g., {Rd, A1} and {Rd, A2}) may be placedon the output port at mapped memory addresses corresponding to the firsttransport technology 712 (e.g., A1), and the second transport technology714 (e.g., A2) and transmitted 716A and 716B on the correspondingtransport technologies to the target TTDM 704.

At the target TTDM 704, the copies of the read request may be receivedat an input port at addresses mapped to the transport technologies. Inthis example, a first copy of the read request may be received ataddress A1 mapped to the first transport technology 718 and a secondcopy of the read request may be received at address A2 corresponding tothe second transport technology 720. The received read requests may beinput to a transaction tracker module 722 of the target TTDM 704 alongwith a source indication that indicates the transport technology thatthe read request was received on (e.g., Src_A1 and Src_A2). A trackingwhiteboard 724 of the target TTDM 704 may be updated with informationabout the received read requests. The tracking whiteboard 724 may recordthe address of the read request (e.g., Addr), as well as addressinformation for received copies of the read request (e.g., SRC1-addr,SRC2-addr) and corresponding request statuses. In this example, thetracking whiteboard 724 has an entry [A, {SRC_A1, recvd}, {SRC_A2,responded}] which indicates that there is an read request to address Awhere a first copy of the request was received at address A1corresponding to the first transport technology, and a second copy ofthe request was received at address A2 corresponding to the secondtransport technology and that a response, from the component has beenreceived. For example, transport technologies may not be synchronous andsome requests may arrive before other requests. In some cases, messageson certain transport technologies may be relayed via other components(not shown). Where the tracking whiteboard 724 indicates that noresponse has been received for the copies of the read requests, a singleread request 728 (e.g., {Rd,A}) for address A may be sent to the targetcomponent.

The transaction tracker module 722 may also allocate space in a sendbuffer 726 to receive responses to the read request from the component.The send buffer 726 may include an address A of the read request, apointer to the FIFO space for storing the response data, and a pointerto the tracker whiteboard 724 index. The send buffer 726 may have asingle space allocated as a single response is expected from the targetcomponent.

The target component may then send a response 730 (e.g., Resp{Rd,A}) tothe target TTDM 704 which is passed to the transaction tracker module722. The response may be stored in the send buffer 726 and the trackingwhiteboard 724 may be updated to indicate that a response has beenreceived. The transaction tracker module 722 may then cause copies ofthe response to be generated and sent via the transport technologies onwhich the requests were received on. In this example, as the trackingwhiteboard 724 indicates that the source of the read request was addressA1, corresponding to the first transport technology, and address A2corresponding to the second transport technology, two copies of theresponse (e.g., Resp{Rd,A1} and Resp{Rd,A2}) may be generated and sent732A and 732B to address A1 corresponding to an address space for thefirst transport technology and address A2 corresponding to an addressspace for the second transport technology. These copies may be placed onthe output port at the mapped memory addresses corresponding to the 718(e.g., A1), and the second transport technology 720 (e.g., A2) andtransmitted 734A and 734B on the corresponding transport technologies tothe requesting TTDM 702.

At the requesting TTDM 702, the copies of the response may be receivedat an input port at addresses mapped to the transport technologies. Inthis example, a first copy of the read request may be received ataddress A1 mapped to the first transport technology 712 and a secondcopy of the read request may be received at address A2 corresponding tothe second transport technology 714. The received responses (e.g.,Resp{Rd,SRC_A1}, Resp{Rd,SRC_A2}) may be input 736A and 735B to thetransaction tracker module 710 of the source TTDM 702 along with asource indication that indicates the transport technology that theresponse was received on (e.g., Src_A1 and Src_A2). The transactiontracker module 710 may determine that the received response satisfy theoperating mode associated with the read request (e.g., any receivedresponse mode, best of N-response mode, etc.). The transaction trackermodule 710 may then select a copy of the received response (e.g.,Resp{Rd,A}) and place the received response on an output port for output738 to the requesting component.

As shown, a fail-safe domain 740 may be defined by the requesting TTDM702 and the target TTDM 704 where a single request may be converted intomultiple independent requests to provide a level of redundancy againsterrors in transmitting the request to the target component andtransmitting the response back to the source component.

FIG. 8 is a flowchart 800 illustrating a technique for transmittingdata, in accordance with aspects of the present disclosure. In somecases, this technique may be performed by an electronic device and/or acircuit. In some cases, instructions for performing this technique maybe stored on a non-transitory computer readable medium, such as flashstorage, magnetic disk, optical media, semiconductor based memorydevices, such as electrically programmable read-only memory (EPROM),electrically erasable programmable read-only memory (EEPROM), etc. Atblock 802, first data associated with a mapped input memory address totransmit to a second component is received from a first component, via amapped input memory address. For example, a local component may senddata for transmission to a remote component (e.g., target component) toa mapped memory location of a TTDM. The TTDM may receive the data via amemory mapped input memory address. In some cases, the TTDM may receivethe data and determine an operating mode. In some cases, the operatingmode may be determined based on a memory range of the mapped memoryinput memory address that the data was received on. At block 804, atleast a first portion of the first data is transmitted, via a firsttransport interface, to the second component. In some cases, the TTDMmay apply the determined operating mode to transmit the data. Forexample, the TTDM may be coupled to multiple transport technologies viamultiple transport interfaces. The TTDM may determine which of thetransport technologies of the multiple transport technologies to use totransmit the data based on the determined operating mode. For example,which transport technology to use may be based on an amount of load onthe transport technologies, a credential associated with the data,and/or an indication that multiple transport technologies should beused. At block 806, a status of the transmission to the second componentmay be recorded. For example, a status of an outstanding transmission tothe remote component may be recorded by the TTDM. At block 808, aresponse to the transmission is received from the second component. Forexample, the response may be received via one or more of the transporttechnologies. At block 810, the response is determined to correspond tothe recorded transmission. For example, the response may include anindication of a corresponding request and the TTDM may map the responseto the corresponding recorded request and update the trackinginformation. At block 812, the response is provided to the firstcomponent. For example, contents of the response may be written to aportion of the mapped memory region to output the contents of theresponse to the local component.

In some cases, another electronic device and/or a circuit may perform atechnique for receiving the transmitted data. In some cases,instructions for performing this technique may be stored on anon-transitory computer readable medium. The technique may includereceiving a first message from a remote component via a first transportinterface. For example, a TTDM may receive data from a remote componentvia a transport technology. In some cases, the component may be coupledto a second transport interface and the component may further receivesecond data from the second transport interface. The received seconddata may be associated with the first message. For example, the firstdata and the second data may both include an indicated address for thetarget component and the first data and second data may be merged to asingle request. In some cases, the first message may be compared to thesecond message to determine that the first message and the secondmessage are different. An indication that an error has been detected maythen be output.

The technique may also include outputting the first message to a localcomponent. For example, the TTDM may output the message to the localcomponent. The TTDM may record the message to help determine a status ofthe message. The outputting may be performed via a memory mapped port.In some cases, the memory mapped port may be presented as a memorymapped region. The technique may also include receiving a response fromthe local component. For example, local component may receive themessage and transmit a response to the message to the TTDM. Thetechnique may also include determining that the received responsecorresponds to the first message from the remote component. For example,the response may include an indication of the message the responsecorresponds to and the TTDM may update the record of the message. Insome cases, the response may be received via a memory mapped inputmemory address. In some cases, the TTDM may receive the response anddetermine an operating mode. In some cases, the operating mode may bedetermined based on a memory range of the mapped memory input memoryaddress that the response was received on. The technique may alsoinclude outputting at least a first portion of the response to theremote component via the first transport interface. For example, theTTDM may output a portion of the response to the transport technologyfor transmission to the remote TTDM. In some cases, the TTDM may applythe determined operating mode to transmit the response. For example, theTTDM may be coupled to multiple transport technologies via multipletransport interfaces. The TTDM may determine which of the transporttechnologies of the multiple transport technologies to use to transmitthe response based on the determined operating mode.

In this description, the term “couple” may cover connections,communications, or signal paths that enable a functional relationshipconsistent with this description. For example, if device A generates asignal to control device B to perform an action: (a) in a first example,device A is coupled to device B by direct connection; or (b) in a secondexample, device A is coupled to device B through intervening component Cif intervening component C does not alter the functional relationshipbetween device A and device B, such that device B is controlled bydevice A via the control signal generated by device A.

Modifications are possible in the described embodiments, and otherembodiments are possible, within the scope of the claims.

What is claimed is:
 1. An electronic device, comprising: a firstcomponent configured to transmit a first set of data to a secondcomponent by providing a first memory request specifying the first setof data and an input memory address; and a transaction tracking unitcoupled to a first transport interface, the transaction tracking unitconfigured to: receive the first memory request; transmit a secondmemory request that specifies at least a first portion of the first setof data, via the first transport interface, to the second component;receive a response to the second memory request from the secondcomponent; determine that the response corresponds to the second memoryrequest; and provide, to the first component, an output response basedon the received response to the second memory request.
 2. The electronicdevice of claim 1, wherein the transaction tracking unit is presented tothe first component as a memory mapped region.
 3. The electronic deviceof claim 2, wherein a transport policy of the transaction tracking unitis based on a sub-region of the memory mapped region that the inputmemory address is located in.
 4. The electronic device of claim 1,wherein the transaction tracking unit is coupled to a second transportinterface, and wherein the transaction tracking unit is furtherconfigured, based on a transport policy, to: transmit at least a secondportion of the first set of data via the second transport interface tothe second component.
 5. The electronic device of claim 4, wherein thefirst transport interface is a different type of transport interfacefrom the second transport interface.
 6. The electronic device of claim4, wherein the second portion is a copy of the first portion.
 7. Theelectronic device of claim 1, wherein the transaction tracking unit isfurther configured, based on a transport policy, to: receive a thirdmemory request specifying a second set of data; determine a transmitorder for portions of the first set of data and the second set of databased on a first type of data associated with the first set of data anda second type of data associated with the second set of data; andtransmit the first set of data and the second set of data based on thetransmit order.
 8. The electronic device of claim 1, wherein thetransaction tracking unit is coupled to a second transport interface andwherein the transaction tracking unit is further configured to: receivethe response via either the first transport interface or the secondtransport interface.
 9. The electronic device of claim 1, wherein thetransaction tracking unit is coupled to a second transport interface andwherein the transaction tracking unit is further configured, based on atransport policy, to: receive a first version of the response via thefirst transport interface; receive a second version of the response viathe second transport interface; compare the first version and the secondversion to determine that the first version and the second version arethe same; and provide one of the first version or the second version ofthe response to the first component via the output response.
 10. Theelectronic device of claim 1, wherein the transaction tracking unit iscoupled to a second transport interface and wherein the transactiontracking unit is further configured, based on a transport policy, to:receive a first version of the response via the first transportinterface; receive a second version of the response via the secondtransport interface; compare the first version and the second version todetermine that the first version and the second version are different;and output an indication that an error has been detected.
 11. Theelectronic device of claim 1, wherein the transaction tracking unit iscoupled to at least three transport interfaces and wherein thetransaction tracking unit is further configured, based on a transportpolicy, to: receive a set of responses via the at least three transportinterfaces; compare responses of the set of responses to determine anoutput version of the response, wherein at least two responses of theset of responses are the same; and provide the output version of theresponse as the output response.
 12. A circuit comprising: a transactiontracking unit configured to: receive a first message from a remotecomponent via a first transport interface; and a memory mapped portcoupled to the transaction tracking unit, the memory mapped portconfigured to: output the first message to a local component; andreceive a response from the local component; wherein the transactiontracking unit is further configured to: determine that the receivedresponse corresponds to the first message from the remote component; andoutput at least a first portion of the response to the remote componentvia the first transport interface.
 13. The circuit of claim 12, whereinthe transaction tracking unit is presented to the local component as amemory mapped region.
 14. The circuit of claim 12, wherein thetransaction tracking unit is coupled to a second transport interface,and wherein the transaction tracking unit is further configured, basedon a transport policy, to: output at least a second portion of theresponse via the second transport interface to the remote component. 15.The circuit of claim 12, wherein the transaction tracking unit iscoupled to a second transport interface, and wherein the transactiontracking unit is further configured to: receive a second message fromthe remote component via the second transport interface; and map thesecond message to the first message.
 16. The circuit of claim 15,wherein the transaction tracking unit is further configured to: comparethe first message and the second message to determine that the firstmessage and the second message are different; and output an indicationthat an error has been detected.
 17. The circuit of claim 15, whereinthe transaction tracking unit is further configured to: determinetransport technologies over which the first and second messages werereceived on; and output the first portion of the response and a secondportion of the response based on the determined transport technologies.18. A method for transmitting data, the method comprising: receiving,from a first component, first data associated with a mapped input memoryaddress to transmit to a second component; transmitting at least a firstportion of the first data, via a first transport interface, to thesecond component; recording an indication of the transmission to thesecond component; receiving a response to the transmission from thesecond component; determining that the response corresponds to therecorded indication of the transmission; and providing the response tothe first component.
 19. The method of claim 18, further comprising:transmitting at least a second portion of the first data via a secondtransport interface to the second component.
 20. The method of claim 19,wherein the first transport interface is a different type of transportinterface from the second transport interface.